Backlight unit

ABSTRACT

Disclosed is a backlight unit. The backlight unit includes a light source, and a cover bottom internally accommodating the light source. Here, the cover bottom is divided into n-numbered (n&gt;1) sub-cover bottoms, and a coupling unit for mutually fixing and coupling the divided cover bottoms is formed at ends of each of the cover bottoms facing each other.

This is a divisional application of copending application Ser. No.14/743,719, filed on Jun. 18, 2015, which is a divisional application ofapplication Ser. No. 13/726,733, filed on Dec. 26, 2012 (now U.S. Pat.No. 9,099,018), which claims the priority benefit of Korean PatentApplication No. 10-2012-0089627 filed in the Republic of Korea on Aug.16, 2012, all of which are hereby incorporated by reference in theirentirety.

BACKGROUND Field of the Disclosure

The present disclosure relates to a backlight unit that is used in adisplay device.

Discussion of the Related Art

A general liquid crystal display device 10 includes a liquid crystalpanel 20 for outputting images, and a cover bottom 30 for receiving theliquid crystal panel 20 therein, as shown in FIG. 1.

On a rear surface of the cover bottom 30, a reinforcement frame 31coupled to upper and lower portions, a reinforcing bar 22 for supportingthe reinforcement frame 31, and a screw type of fixing member 33 forfixing and coupling the reinforcing bar 22 and the cover bottom 30 arepositioned.

More specifically, the cover bottom 30 is manufactured in the form of asingle sheet metal so as to correspond to a size (inch) of the liquidcrystal panel 20, and the cover bottom 30 is laterally distorted due tothermal deformation occurring with respect to the reinforcing bar 22 byheat generated in a light source, thereby adversely affecting themechanical life of the liquid crystal display device 10.

In addition, it is difficult to manufacture and mold the cover bottom inthe form of a single sheet metal corresponding to a size of a liquidcrystal panel which has been rapidly increasing.

In addition, along with the increase in the size of the cover bottom, aplurality of reinforcing bars should be provided on a rear surface ofthe cover bottom, resulting in an increase in manufacturing costs.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a backlight unit for adisplay device that substantially obviates one or more of the problemsdue to limitations and disadvantages of the related art.

An object of the present disclosure is to provide a backlight unit for adisplay device which may prevent thermal expansion and thermaldeformation of the backlight unit affected by heat generated from alight source of a large display device, and include a cover bottomdivided into a plurality of parts and joined to one so as to withstandexternal shocks.

Additional features and advantages of the invention will be set forth inthe description which follows, and in part will be apparent from thedescription, or may be learned by practice of the invention. Theobjectives and other advantages of the invention will be realized andattained by the structure particularly pointed out in the writtendescription and claims hereof as well as the appended drawings.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described herein, abacklight unit includes: a light source; and a cover bottom internallyaccommodating the light source, wherein the cover bottom is divided inton-numbered (n>1) sub-cover bottoms, and a coupling unit for mutuallyfixing and coupling the divided sub-cover bottoms is formed at ends ofeach of the cover bottoms facing each other.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention. In the drawings:

FIG. 1 is a perspective view showing a liquid crystal display device ofthe related art;

FIG. 2 is an exploded perspective view showing a display deviceaccording to an embodiment of the present invention;

FIG. 3 is a sectional view showing a coupled cover bottom constituting abacklight unit according to a first embodiment of the present invention;

FIG. 4 is a sectional view showing a state in which an alignment memberand a coupling member are coupled to a cover bottom shown in FIG. 3;

FIG. 5 is a sectional view showing a coupled cover bottom constituting abacklight unit according to a second embodiment of the presentinvention;

FIG. 6 is a sectional view showing a coupled cover bottom constituting abacklight unit according to a third embodiment of the present invention;

FIGS. 7A to 7C are perspective views showing a coupling process of thecover bottom shown in FIG. 6;

FIG. 8 is a perspective view showing a coupled cover bottom constitutinga backlight unit according to a fourth embodiment of the presentinvention;

FIG. 9A is a perspective view showing a coupled cover bottomconstituting a backlight unit according to a fifth embodiment of thepresent invention;

FIG. 9B is a sectional view showing a coupling process of a cover bottomconstituting a backlight unit according to a fifth embodiment of thepresent invention;

FIG. 10 is a perspective view showing a coupled cover bottomconstituting a backlight unit according to a sixth embodiment of thepresent invention;

FIG. 11 is a perspective view showing a coupled cover bottomconstituting a backlight unit according to a seventh embodiment of thepresent invention; and

FIG. 12 is a perspective view showing a reinforcing member constitutinga backlight unit according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Example embodiments of the present invention are described below insufficient detail to enable those of ordinary skill in the art to embodyand practice the present invention. It is important to understand thatthe present invention may be embodied in many alternate forms and shouldnot be construed as limited to the example embodiments set forth herein.It will be understood that, although the terms first, second, A, B, etc.may be used herein in reference to elements of the invention, suchelements should not be construed as limited by these terms.

Hereinafter, preferred embodiments of the present invention will bedescribed in more detail in reference with the accompanying drawings.Throughout the accompanying drawings, the same reference numerals areused to designate the same or similar components, and redundantdescriptions thereof are omitted for easier overall understanding.

FIG. 2 is an exploded perspective view showing a display device 100according to an embodiment of the present invention. As shown in FIG. 2,the display device 100 includes a panel 110, a backlight unit, a guidepanel 153, and a top case 154. Here, the backlight unit is composed of alight source 120, a light guide plate 130, a cover bottom 140, areflecting sheet 151, and an optical sheet 152.

More specifically, the panel 110 may be composed of a liquid crystalpanel in which a liquid crystal layer is formed between a colorsubstrate and an array substrate so as to output images.

In addition, the light source 120 is positioned below the panel 110 soas to emit light to the panel 110, and is composed of an LED assembly inwhich a plurality of LEDs 122 are mounted on a printed circuit board121.

The light guide plate 130 makes the light emitted from the LED 122incident to the panel 110, and is preferably provided so as to face anemission direction of the LED 122.

In addition, the cover bottom 140 constituting the backlight unit ispositioned below the light guide plate 130, and internally accommodatesthe panel 110 and the light source 120.

More specifically, the cover bottom 140 according to an embodiment ofthe present invention is divided into n-numbered (n>1, n being a naturalnumber) cover bottoms.

In addition, in an A region of the cover bottom 140 shown in FIG. 2, acoupling unit for fixing and coupling ends of the cover bottoms facingeach other is formed, and the coupling unit A will be described infurther detail described below.

Both ends of the cover bottom coupled to the outermost angle of thecover bottom 140 are bent orthogonally to the direction of the panel110, and therefore the cover bottom internally accommodates the lightguide plate 130, the reflecting sheet 151, and the optical sheet 152.

The reflecting sheet 151 according to an embodiment of the presentinvention shown in FIG. 2 is positioned between the light guide plate130 and the cover bottom 140, and re-reflects light leaked to theoutside of the light guide plate 130, which cannot be propagated intothe light guide plate 130, to a front surface of the panel 110.

The optical sheet 152 is positioned between the panel 110 and the lightguide plate 130, and is composed of a prism sheet for condensing thelight passing through the light guide plate 130 and a diffusion sheetfor diffusing light.

In addition, the guide panel 153 guides the panel 110, and fixes theoptical sheet 152.

The top case 154 covers edges of an upper surface of the panel 110, andis coupled to the cover bottom along a side border of the guide panel153 and the cover bottom 140, and therefore the panel 110 and thebacklight unit are integrated.

FIG. 3 is a sectional view showing a coupled cover bottom constituting abacklight unit according to a first embodiment of the present invention.

An example in which the cover bottom is divided into two will bedescribed. As shown in FIG. 3, the cover bottom 140 a is divided into aplurality of cover bottoms 141 a and 142 a, and a coupling unit A forfixing and coupling ends of the cover bottoms 141 a and 142 a isprovided.

More specifically, according to the first embodiment, each of the firstcover bottom 141 a and the second cover bottom 142 a positioned adjacentto the first cover bottom 141 a includes a bent region in which ends ofthe first and second cover bottoms 141 a and 142 a are bent by 180degrees so as to form a hemming structure by a hemming process.

Next, the second cover bottom 142 a is laminated on the first coverbottom 141 a.

In this manner, a total of four sheet metals of the cover bottom 140 aconstituting the coupling unit A may be laminated, and the number oflaminated sheet metals may be variously changed depending on the numberof times of the hemming process performed on the end of the coverbottom.

In addition, since the coupling unit A is formed in such a manner thatmultiple sheet metals of the divided cover bottoms are laminated, athickness of the coupling unit A may be variously changed depending onthe size of the panel, and therefore hardness of the cover bottom 140 aconstituting the backlight unit according to the present invention isimproved compared to the cover bottom of the related art to which areinforcing bar is coupled.

Accordingly, the coupling unit A may replace a plurality of reinforcingbars provided so as to maintain hardness of the cover bottom accordingto the related art, thereby reducing manufacturing costs.

When high heat generated from a plurality of LEDs 122 constituting thelight source 120 is transmitted to the cover bottom 140 a, the dividedcover bottoms 141 a and 142 a may individually enable thermal expansionand thermal contraction.

Therefore, an amount of deformation is offset due to thermal deformationin the bent region constituting the coupling unit A, and therefore thereis an effect of preventing distortion of the cover bottom 140 aoccurring due to heat.

FIG. 4 is a sectional view showing a state in which an alignment memberand a coupling member are coupled to a cover bottom shown in FIG. 3. Asshown in FIG. 4, the coupling unit A further includes a plurality ofalignment members 161 and a fastening member 162.

More specifically, the alignment member 161 acts as a PEM nut, andthereby passes through a laminated region of the first cover bottom 141a and the second cover bottom 142 a so as to guide lamination of thedivided cover bottoms 140 a, and align the divided cover bottoms 140 a.

In addition, the alignment member 161 may fix and couple the laminatedcover bottoms 140 a with each other in addition to guide the laminationof the first and second cover bottoms 141 a and 142 a, and align thefirst and second cover bottoms 141 a and 142 a.

The fastening member 162 may fix and couple the divided cover bottoms140 a with each other.

More specifically, as shown in FIG. 3, the screw type of fasteningmember 162 according to an embodiment of the present invention includesa thread formed on an outer circumferential surface thereof, and passesthrough the first cover bottom 141 a and the second cover bottom 142 ato fix and couple the first and second cover bottoms 141 a and 142 a.

In addition, the fastening member 162 may select and change a variety ofmeans for fixing the cover bottom 140 a which has been divided into theplurality of cover bottoms to be laminated.

FIG. 5 is a sectional view showing a coupled cover bottom constituting abacklight unit according to a second embodiment of the presentinvention. In the following description of the second embodiment, thesame components as or corresponding to those in the above-describedfirst embodiment will be omitted. Hereinafter, with reference to FIG. 5,the cover bottom according to the second embodiment will be described.

A cover bottom 140 b according to the second embodiment of the presentinvention is divided into a plurality of cover bottoms 141 b and 142 b,and ends of the divided cover bottoms 141 b and 142 b are fixed andcoupled with each other to thereby constitute a coupling unit A.

More specifically, according to the second embodiment shown in FIG. 5,each of the first cover bottom 141 b and the second cover bottom 142 bpositioned adjacent to the first cover bottom 141 b includes a bentregion in which ends of the first and second cover bottoms 141 b and 142b are bent by 180 degrees so as to form a hemming structure by a hemmingprocess.

Next, the second cover bottom 142 b is laminated on the first coverbottom 141 b to form the coupling unit A so that an end of the secondcover bottom 142 b faces an end of the first cover bottom 141 b.

Accordingly, a total of three sheet metals of the cover bottom 140 bconstituting the coupling unit A may be laminated, and the number oflaminated sheet metals may be variously changed depending on the numberof times of the hemming process performed on the end of the coverbottom.

In addition, since the coupling unit A is formed in such a manner thatmultiple sheet metals of the divided cover bottoms are laminated, athickness of the coupling unit A may be variously changed depending onthe size of a panel, and therefore hardness of the cover bottom 140 bconstituting the backlight unit according to the present invention isimproved compared to the cover bottom of the related art to which areinforcing bar is coupled.

Accordingly, the coupling unit A may replace a plurality of reinforcingbars provided so as to maintain hardness of the cover bottom accordingto the related art, thereby reducing manufacturing costs.

When high heat generated from a plurality of LEDs 122 constituting thelight source 120 is transmitted to the cover bottom 140 b, the dividedcover bottoms 141 b and 142 b may individually enable thermal expansionand thermal contraction.

Therefore, an amount of deformation is offset due to thermal deformationin the bent region constituting the coupling unit A, and therefore thereis an effect of preventing distortion of the cover bottom 140 boccurring due to heat.

In addition, although not shown, in the same manner as in the firstembodiment shown in FIG. 4, a plurality of alignment members andfastening members may be coupled to the coupling unit A of the coverbottom 140 b according to the second embodiment.

FIG. 6 is a sectional view showing a coupled cover bottom constituting abacklight unit according to a third embodiment of the present invention,and FIGS. 7A to 7C are perspective views showing a coupling process ofthe cover bottom shown in FIG. 6.

In the following description of the third embodiment, the samecomponents as or corresponding to those in the above-described first andsecond embodiments will be omitted. Hereinafter, with reference to FIGS.6 and 7A to 7C, the cover bottom according to the third embodiment willbe described.

As shown in FIG. 6, a cover bottom 140 c according to the thirdembodiment of the present invention is divided into a plurality of coverbottoms 141 c and 142 c, and ends of the divided cover bottoms 141 c and142 c are fixed and coupled with each other to thereby constitute acoupling unit A.

More specifically, according to the third embodiment shown in FIG. 6,the first cover bottom 141 c includes a bent region in which an end ofthe first cover bottom 141 c is bent by 180 degrees so as to form ahemming structure by a hemming process, and a predetermined space may beformed in the bent region.

In addition, the second cover bottom 142 c positioned adjacent to thefirst cover bottom 141 c includes a bent region in which an end of thesecond cover bottom 142 c is bent by 180 degrees so as to form a hemmingstructure by a hemming process, and a predetermined space may be formedin the bent region.

In order to insert the second cover bottom 142 c into the space formedin the bent region of the first cover bottom 141 c, as shown in FIG. 7A,the second cover bottom 142 c is positioned on the first cover bottom141 c.

Next, as shown in FIG. 7B, the second cover bottom 142 c is moved in adirection of an arrow, so that the predetermined space formed in thebent region of the first cover bottom 141 c and the predetermined spaceformed in the bent region of the second cover bottom 142 c face eachother.

Next, as shown in FIG. 7C, the second cover bottom 142 c is moved in adirection of an arrow, so that the second cover bottom 142 c is slidablycoupled to the predetermined space formed in the bent region of thefirst cover bottom 141 c.

In addition, as shown in FIG. 7C, by pressuring, in a press process, alaminated region from below and above in a state in which sheet metalsof the first cover bottom 141 c and the second cover bottom 142 c arealternately laminated, the coupling unit A for fixing and coupling thefirst cover bottom 141 c and the second cover bottom 142 c may beformed.

Therefore, a total of three sheet metals of the cover bottom 140 cconstituting the coupling unit A may be laminated, and the number oflaminated sheet metals may be variously changed depending on the numberof times of the hemming process performed on the end of the coverbottom.

According to the present embodiment, since the first cover bottom 141 cand the second cover bottom 142 c are hooked and coupled with eachother, hardness of the cover bottom 140 c constituting the backlightunit according to the present invention is improved compared to thecover bottom of the related art to which a reinforcing bar is coupled.

In addition, the coupling unit A may replace a plurality of reinforcingbars provided so as to maintain hardness of the cover bottom of therelated art, thereby reducing manufacturing costs.

When high heat generated from a plurality of LEDs 122 constituting thelight source 120 is transmitted to the cover bottom 140 c, the dividedcover bottoms 141 c and 142 c may individually enable thermal expansionand thermal contraction.

Therefore, an amount of deformation is offset due to thermal deformationin the bent region constituting the coupling unit A, and therefore thereis an effect of preventing distortion of the cover bottom 140 coccurring due to heat.

In addition, although not shown, in the same manner as in the firstembodiment shown in FIG. 4, a plurality of alignment members andfastening members may be coupled to the coupling unit A of the coverbottom 140 c according to the third embodiment.

FIG. 8 is a perspective view showing a coupled cover bottom constitutinga backlight unit according to a fourth embodiment of the presentinvention. In the following description of the fourth embodiment, thesame components as or corresponding to those in the above-describedembodiments will be omitted. Hereinafter, with reference to FIG. 8, thecover bottom according to the fourth embodiment will be described.

As shown in FIG. 8, the second cover bottom 142 c may include a formingshape 145 c in a region excluding a region where the second cover bottom142 c and the first cover bottom 141 c are coupled with each other,using a forming method.

More specifically, in a structure of the cover bottom 140 c, the formingshape 145 c including a predetermined space 147 c is formed on theuppermost sheet metal of a coupling unit A formed such that sheet metalsof the first and second cover bottoms 141 c and 142 c are alternatelylaminated, and therefore hardness of the cover bottom 140 c may beimproved.

In addition, although not shown, in the same manner as in the firstembodiment shown in FIG. 4, a plurality of alignment members andfastening members may be coupled to a laminated region of the coverbottom 140 c according to the fourth embodiment.

FIG. 9A is a perspective view showing a coupled cover bottomconstituting a backlight unit according to a fifth embodiment of thepresent invention, and FIG. 9B is a sectional view showing a couplingprocess of a cover bottom constituting a backlight unit according to afifth embodiment of the present invention. In the following descriptionof the fifth embodiment, the same components as or corresponding tothose in the above-described embodiments will be omitted. Hereinafter,with reference to FIGS. 9A and 9B, the cover bottom according to thesecond embodiment will be described.

As shown in FIG. 9B, the first cover bottom 141 e and the second coverbottom 142 e are laminated in a predetermined region.

Next, the laminated region is positioned on a press die D including atox (T) shape.

Next, a pressing process is performed using a press machine (M), andthen a coupling unit A is formed on the laminated region of the coverbottom 140 c, and therefore the first cover bottom 141 e and the secondcover bottom 142 e are fixed and coupled with each other.

Accordingly, according the fifth embodiment of the present invention,the same alignment member and fastening member as in the firstembodiment may not be provided in the coupling unit A of the coverbottom 140 e.

Therefore, the coupling unit A according to the present embodiment mayreplace a plurality of reinforcing bars provided to maintain hardness ofthe cover bottom according to the related art, thereby reducingmanufacturing costs.

FIG. 10 is a perspective view showing a coupled cover bottomconstituting a backlight unit according to a sixth embodiment of thepresent invention. In the following description of the sixth embodiment,the same components as or corresponding to those in the above-describedembodiments will be omitted. Hereinafter, with reference to FIG. 10, thecover bottom according to the sixth embodiment will be described.

As shown in FIG. 10, it is preferable that a coupling unit A of a coverbottom 140 f formed such that the cover bottom 140 f is divided into aplurality of cover bottoms, and the divided cover bottoms are integrallycoupled with each other be formed in a direction opposite to the liquidcrystal panel 110.

More specifically, the coupling unit A includes a fixing member 149 fthat is slidably coupled with a plurality of bent portions B along anouter circumferential surface of the bent region B.

As shown in FIG. 10, the bent portion B formed at an end of a firstcover bottom 141 f includes a vertical portion 143 f that is bent in thedirection opposite to the liquid crystal panel, and an extended portion145 f that is extended from the vertical portion 143 f and is horizontalwith the first cover bottom 141 f.

The bent portion B formed at an end of a second cover bottom 142 f alsoincludes a vertical portion 144 f and an extended portion 146 f so as tocorrespond to the bent portion B of the first cover bottom 141 f.

In addition, as shown in FIG. 10, it is preferable that a bent anglebetween the bent portions B be perpendicular.

In addition, as shown in FIG. 10, the fixing member 149 f is slidablycoupled along an outer circumferential surface of the bent portion B,and therefore the first cover bottom 141 f and the second cover bottom142 f are integrally fixed and coupled to each other.

Therefore, a coupling unit A according to the present embodiment mayreplace a plurality of reinforcing bars so as to maintain hardness ofthe cover bottom according to the related art, thereby reducingmanufacturing costs.

When high heat generated from a plurality of LEDs 122 constituting thelight source 120 is transmitted to the cover bottom 140 f, the dividedcover bottoms 141 f and 142 f may individually enable thermal expansionand thermal contraction.

Therefore, an amount of deformation is offset due to thermal deformationin the bent portion B constituting the coupling unit A, and thereforethere is an effect of preventing distortion of the cover bottom 140 foccurring due to heat.

In addition, according to the sixth embodiment of the present invention,since the fixing member 149 f fixes and couples the first and secondcover bottoms 141 f and 142 f, the cover bottom 140 f may notadditionally include an alignment member or a fastening member.

FIG. 11 is a perspective view showing a coupled cover bottomconstituting a backlight unit according to a seventh embodiment of thepresent invention. In the following description of the seventhembodiment, the same components as or corresponding to those in theabove-described embodiments will be omitted. Hereinafter, with referenceto FIG. 11, the cover bottom according to the second embodiment will bedescribed.

As shown in FIG. 11, compared to the coupling unit A of the cover bottom140 f according to the sixth embodiment, a bent that is bent in adirection of a cover bottom 140 g may be further included.

More specifically, the coupling unit A includes a fixing member 149 gthat is slidably coupled to a plurality of bent portions B along anouter circumferential surface of the bent portion B.

As shown in FIG. 11, the bent portion B that is formed at an end of thefirst cover bottom 141 g includes a vertical portion 143 g, an extendedportion 145 g, and a bent 147 g.

The vertical portion 143 g is bent from an end of the first cover bottom141 g in a direction opposite to the liquid crystal panel 110.

In addition, the extended portion 145 g is extended from the verticalportion 143 g so as to be horizontal with the first cover bottom 141 g.

The bent 147 g is bent from an end of the extended portion 145 g in adirection of the first cover bottom 141 g.

Accordingly, a bent portion B formed at an end of the second coverbottom 142 g also includes a vertical portion 144 g, an extended portion146 g, and a bent 148 g so as to correspond to the bent portion B of thefirst cover bottom 141 g.

As shown in FIG. 11, a bent angle formed between the bent portions B maybe variously formed.

More specifically, each angle between the vertical portions 143 g and144 g and the extended portions 145 g and 146 g may be 90 degrees, andeach angle between the extended portions 145 g and 146 g and the bents147 g and 148 g may be 45 degrees or less.

In addition, as shown in FIG. 11, the fixing member 149 g is slidablycoupled along an outer circumferential surface of the bent portion B,and therefore the first cover bottom 141 g and the second cover bottom142 g may be integrally fixed and coupled with each other.

Therefore, the coupling unit A according to the present embodiment mayreplace a plurality of reinforcing bars provided so as to maintainhardness of the cover bottom according to the related art, therebyreducing manufacturing costs.

When high heat generated from a plurality of LEDs 122 constituting thelight source 120 is transmitted to the cover bottom 140 g, the dividedcover bottoms 141 g and 142 g may individually enable thermal expansionand thermal contraction.

Therefore, an amount of deformation is offset due to thermal deformationin the bent region B constituting the coupling unit A, and thereforethere is an effect of preventing distortion of the cover bottom 140 goccurring due to heat.

In addition, according to the seventh embodiment of the presentembodiment, since the fixing member 149 g fixes and couples the firstand second cover bottoms 141 g and 142 g, the cover bottom 140 g may notadditionally include an alignment member or a fastening member.

FIG. 12 is a perspective view showing a reinforcing member 170constituting a backlight unit according to an embodiment of the presentinvention.

As shown in FIG. 12, the reinforcing member 170 includes a firstreinforcing portion 171, a second reinforcing portion 173, and aconnection member 177, which may be commonly applied to the cover bottomaccording to the first to seventh embodiments of the present invention.

More specifically, as shown in FIG. 12, the first reinforcing portion171 includes a coupling groove 172 formed on an inner surface thereoffacing the cover bottom, and an opening 175 formed at ends of both sidesthereof.

Accordingly, the first reinforcing portion 171 is coupled to the coverbottom along a length direction of the cover bottom to thereby supportthe length direction of the cover bottom.

In addition, in the same manner as in the first embodiment, the secondreinforcing portion 173 includes a coupling groove 172 formed on aninner surface thereof facing the cover bottom, and an opening 175 formedat ends of the both sides thereof.

Accordingly, the second reinforcing portion 173 is coupled to the coverbottom along a width direction of the cover bottom to thereby supportthe width direction of the cover bottom.

A side surface of the cover bottom 140 of FIG. 2 is inserted into thecoupling groove 172 of the first and second reinforcing portions 171 and173.

The connection member 177 connects an end of the first reinforcingportion 171 and an end of the second reinforcing portion 173. Here, oneend of the connection member 177 is inserted and fixed in the opening175 of the first reinforcing portion 171, and the other end thereof isinserted and fixed in the opening 175 of the second reinforcing portion173.

That is, the reinforcing member 170 according to the embodiments of thepresent invention is coupled to the cover bottom along a side border ofthe cover bottom 140 of FIG. 2 which has been divided into a pluralityof cover bottoms and integrally coupled, thereby forming a verticalpartition on an inclined surface of the cover bottom 140 of FIG. 2.

Therefore, the reinforcing member 170 is coupled to the cover bottom soas to cover the entire side border of the cover bottom 140, therebypreventing damage and deformation of the cover bottom 140 occurring dueto external shocks.

In addition, when high heat generated from the light source 120 istransmitted to the cover bottom 140 so that expansion and contractionrepeatedly occur over the entire surface of the cover bottom 140, thereinforcing member 170 supports the cover bottom 140 in the lengthdirection and width direction of the cover bottom 140, therebypreventing distortion of the cover bottom 140 due to heat.

As described above, according to the embodiments of the presentinvention, the cover bottom constituting the backlight unit is formed ina division structure in which the cover bottom is divided into aplurality of cover bottoms, thereby preventing thermal expansion of thecover bottom due to heat generated from the light source, and thermaldeformation due to the thermal expansion.

In addition, the cover bottom is formed in a division structure, andtherefore hardness of the cover bottom is improved compared to the coverbottom of the related art including a reinforcing bar, thereby stablysupporting a panel constituting a large display device, and protectingthe display device from external shocks.

In addition, the coupling unit replaces a reinforcing bar provided on abottom surface of a cover bottom of a liquid crystal display deviceaccording to the related art, thereby reducing manufacturing costs, andimproving production yield.

In addition, compared to the cover bottom of the related art which isformed as a single sheet metal, the cover bottom according to thepresent invention has a division structure, and therefore extension isfacilitated in response to the size of a panel which has beenincreasingly larger.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in a backlight unit of thepresent disclosure without departing from the sprit or scope of theinvention. Thus, it is intended that the present invention covers themodifications and variations of this invention provided they come withinthe scope of the appended claims and their equivalents.

What is claimed is:
 1. A backlight unit comprising: a light source; anda cover bottom internally accommodating the light source, wherein thecover bottom is divided into n-numbered (n>1) sub-cover bottoms, and acoupling unit for mutually fixing and coupling the sub-cover bottoms isformed at ends of each of the sub-cover bottoms facing each other, andwherein the coupling unit includes a bent region formed such that an endof an n-th sub-cover bottom is bent, and a bent region formed such thatan end of an (n+1)-th sub-cover bottom is bent, and the (n+1)-th bentregion is internally hooked and coupled to the n-th bent region and the(n+1)-th sub-cover bottom is positioned on the n-th sub-cover bottom sothat sheet metals of the n-th sub-cover bottom and the (n+1)-thsub-cover bottom are alternately laminated.
 2. The backlight unit ofclaim 1, wherein a forming shape is formed on the uppermost sheet metalof a laminated region formed such that the sheet metals of the n-thsub-cover bottom and the (n+1)-th sub-cover bottom are alternatelylaminated.
 3. The backlight unit of claim 1, wherein the bent region iscomposed of a hemming structure.
 4. The backlight unit of claim 1,wherein the coupling unit further includes a plurality of alignmentmembers passing through the laminated region so as to align the dividedsub-cover bottoms, and a plurality of fastening members passing throughthe laminated region to be coupled with the divided sub-cover bottoms soas to fix and couple the divided sub-cover bottoms.
 5. The backlightunit of claim 1, further comprising: a light guide plate provided so asto face the light source; a reflecting sheet positioned below the lightguide plate and reflecting light leaked from the light guide plate; anoptical sheet positioned above the light guide plate and condensing anddiffusing light passing through the light guide plate; and a reinforcingmember coupled to outer surfaces of the divided sub-cover bottoms andsupporting the cover bottom, wherein the light source is formed as anLED assembly in which a plurality of LEDs are mounted on a printedcircuit board.
 6. The backlight unit of claim 5, wherein the reinforcingmember includes a first reinforcing portion including a coupling grooveformed on an inner surface thereof and coupled along a length directionof the cover bottom to support the cover bottom, a second reinforcingportion including a coupling groove formed on an inner surface thereofand coupled along a width direction of the cover bottom to support thecover bottom, and a connection member connecting an end of the firstreinforcing portion and an end of the second reinforcing portion.
 7. Thebacklight unit of claim 6, wherein an opening is formed at both the endsof the first and second reinforcing portions, one end of the connectionmember is inserted and fixed in the opening of the first reinforcingportion, and the other end thereof is inserted and fixed in the openingof the second reinforcing portion.